Based　on　the　combination　of　state　matrix　and　Legendre　series　method　with　Biot＇s　theory,　a　theoretical　model　for　wave　propagation　in　multi-layered　porous　lithium-ion　batteries　is　established.　Taking　1.9　mm-thick　soft-pack　cobalt　oxides　lithium-ion　battery　as　an　example,　the　influence　of　State　Of　Charge　(SOC)　on　the　multi-mode　dispersion　curves　is　numerically　analyzed.　At　the　same　time,　a　frequency-domain　simulation　model　of　the　wave　propagation　characteristics　of　a　multilayer　porous　lithium-ion　battery　is　established,　and　the　ultrasonic　guided　wave　dispersion　curves　in　frequency-domain　simulation　are　extracted.　In　addition,　based　on　Macro　Fiber　Composite　(MFC)　transducer　which　possesses　small　volume　and　strong　flexibility,　the　influence　of　different　states　of　charge　on　the　acoustic　behavior　of　lithium-ion　batteries　is　explored　experimentally.　The　cross-correlation　analysis　is　used　to　obtain　the　shift　in　the　time　of　flight　during　the　discharging　process.　The　mapping　relationship　between　acoustic　wave　behavior　and　SOC　of　a　1.9　mm-thick　soft-pack　cobalt　oxides　lithium-ion　battery　is　established.　©　2022　Acta　Acustica.